With this property, users can control if this filter is 'on'
or 'off'. The default behavior for filter is 'on'.

For some types of filters, they may need to react to status changing,
So here, we introduced status changing callback/notifier for filter class.

We will skip the disabled ('off') filter when delivering packets in net layer.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Yang Hongyang <hongyang.yang@easystack.cn>
Signed-off-by: Jason Wang <jasowang@redhat.com>